Probing the anomalous FCNC interactions in a top-Higgs boson final state and the charge ratio approach

We study the anomalous production of a single top quark in association with a Higgs boson at the LHC originating from flavor-changing neutral current interactions in tqg and tqH vertices. We derive the discovery potentials and 68% C.L. upper limits considering leptonic decay of the top quark and the Higgs boson decay into a b (b) over bar pair with 10 fb(-1) integrated luminosity of data in proton-proton collisions at the center-of-mass energy of 14 TeV. We propose a charge ratio for the lepton in top quark decay in terms of lepton p(T) and eta as a strong tool to observe the signal. In particular, we show that the charge ratio increases significantly at large p(T) of the charged lepton, while the main background from t (t) over bar is nearly charge symmetric and the W+ jets background has much smaller charge ratio with respect to the signal. We show that this feature can also be used in the probe of anomalous single top production with a Z boson or a photon that is under the attention of the experimental collaborations.